A process of forming a coating film on a surface of a substrate is one of semiconductor manufacturing processes. Examples of the coating film may include a resist film, an anti-reflection film, an organic film or an insulating film serving as an etching mask, and the like. In the process of forming the coating film, spin coating is mainly used in which a chemical liquid is spread by rotating a substrate, and a liquid film of the chemical liquid is formed on the entire surface of the substrate by the spin coating. Since the liquid film is wrapped around a peripheral portion of the substrate when the liquid film is formed, a film is peeled off from the peripheral portion and therefore results in particle contamination. Alternatively, a film is attached to a transfer arm when the substrate is transferred by the transfer arm, and therefore, a subsequent substrate may be contaminated when the transfer arm transfers the subsequent substrate.
For this reason, after a coating film is formed on a surface of a substrate, a process for removing the coating film at a peripheral portion of the substrate is performed by a chemical liquid for removing the coating film, e.g., a solvent. When the substrate is a semiconductor wafer, after the spin coating is terminated, the process is performed in such a manner that the solvent is discharged from a nozzle to the peripheral portion of the substrate while the substrate is rotated using a spin chuck.
Meanwhile, there is a request for allowing a formation region of a device to approach the circumferential end of a substrate as close as possible in order to make effective use of the substrate. In order to meet the request, it is necessary to allow the removal width of a coating film at the peripheral portion of the substrate to be as narrow as possible and uniform in the circumferential direction. In this respect, before a coating film forming apparatus is operated, it is required to perform the fine control on a discharge state of a solvent from a nozzle (including a non-discharge state). The control is performed while an operator observes the discharge state of the solvent from the nozzle with the naked eye. The coating film forming apparatus, together with a heating unit or a transfer system, is generally disposed in a housing. In addition, the coating film forming apparatus is configured such that some components of a supply control device of a chemical liquid, such as a cup module for performing the spin coating, a discharge nozzle of the chemical liquid, and a valve, are accommodated in a case body.
For this reason, the operator should observe a discharge state of the solvent from the nozzle within the narrow and dark apparatus in which members are densely aggregated. Therefore, although the operator lights the inside of the apparatus using a flashlight, it is difficult to perform an operation. In particular, it is difficult to determine whether any splash occurs, or the like. In addition, since the determination of whether the discharge state is satisfactory is made by operator's experience, it is unavoidable that the determination includes a difference between individuals. For example, a technique has been proposed in which a discharge direction of a removal liquid is adjusted by picking up images of directions that the removal liquid of a coating film is discharged to a peripheral portion of a substrate and the removal liquid is scattered from the peripheral portion by a CCD camera. However, the technique is not to adjust the discharge state or the non-discharge state of the removal liquid from a nozzle.